1. Field of the Invention
In general, the present invention relates to original equipment manufacturer (OEM) components/parts/assemblies, new and replacement, which are located or built within a volume or chamber where access is limited; such as is the case with deaerator tanks within which plate assemblies are initially built, and at some point in time typically need replacing due to caustic conditions, extreme temperature fluctuations and low pressure(s) to which the plate assembly is exposed.
2. Background of the Invention
More-particularly, applicants' invention is directed to a unique segmented plate and associated plate assembly technique, adapted for use where access is limited to an area/chamber within which the plate is to be secured and employed for use in connection with an enclosure. While focus of the embodiments depicted and described herein is within the context of power plant boiler systems, and more-particularly, this discussion is directed towards use of applicants' segmented plate in deaerator tanks where water treatment takes place to mechanically reduce dissolved oxygen levels from the water before it flows into the boiler system, the plate assembly of the invention may be used in a wide variety of contexts in connection with a equipment having areas/chambers to which access is limited.
As is well known, deaerator tanks have chambers with limited access: the tray enclosure within which the deaerating process takes place typically has a nozzle-vent body assembly through which steam passes and non-condensable gases (e.g., oxygen, carbon dioxide) may pass. In many cases, the geometric size of internal assemblies make it difficult, if not impossible, to build or repair a damaged assembly having an exterior perimeter larger than will fit through the limited access. The segmented plate of the invention provides a unique solution for those responsible for regular power plant deaerator maintenance. Applicants' unique segmented plate design may be used as a replacement for unitary plates currently built into new OEM deaerator tanks around a nozzle-vent body assembly of the tray enclosure, as well as initially installed by an OEM when a new tank product is manufactured. Use of the segmented plate of the invention makes the disassembly and removal of a cracked, fractured, or otherwise damaged tray box's plate, less difficult. Again, and as one will appreciate, the segmented plate and associated plate assembly technique of the invention may be employed in a variety of other contexts where access to an area/chamber within which the plate is to operate, is limited.
It is preferable to keep maintenance downtime associated with tearing-down and rebuilding sub-assemblies of any system to a minimum; this is typically true, whether or not the reason for requiring a repair/rebuild is critical to overall system performance and operation. In the case of power plants, taking a plant ‘off-line’, or shutting down a major component of the plant for repair, can become very costly. Operating a power plant at less than optimal efficiency can likewise be very costly. One widely used treatment of water in power plants, known as deaerating, is done to remove oxygen from the water flowing into and through the boiler. The removal of oxygen using a deaerator assembly is important, as dissolved oxygen that remains in boiler water interacts with boiler component surfaces. Feedwater with dissolved oxygen leads to carbon doioxide dissolved in water. This lowers the feedwater pH levels and produces corrosive carbonic acid. Typically, a deaerator tank encloses some type of deaerating assembly; the deaerating assembly may be a tray type assembly enclosed to carry out the process of deaeration. Currently, as depicted schematically in FIG. 1 hereof, certain deaerator unit designs incorporate a unitary stainless steel plate bolted to the tray enclosure; this unitary rectangular plate 10 acts as a support for a centrally located nozzle body-vent assembly 14 through which steam is passed and unwanted/excess oxygen gas is vented to carry out deaeration.
When a unitary plate assembly such as that shown in FIG. 1 at 10 in operation secured to a tray enclosure within a deaerator tank 20 to which access 22 is limited, cracks or is otherwise damaged due to the caustic conditions to which the plate is exposed under normal, continuous use, unless the tank 20 can be disassembled (typically an onerous job) to provide more access, the damaged plate can only be replaced after it has been destroyed—for example, by using a torch or other metal cutting tool—and removed, piece-by-piece. Where a deaerator tank 20 is cumbersome to disassemble, or if the tank has no mechanism for disassembly except to torch (or otherwise) open a larger access so that replacement of a damaged plate may be made with another unitary plate, replacement of the new unitary plate may take an extraordinary amount of downtime, effort, and expense. Applicants have developed a unique segmented plate structure and associated assembly technique that attends to this problem in the context of deaerator tank fabrication and maintenance, as well as provides further alternatives to assembling plate structures in a host of other environments.